<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="./vue.js"></script>
</head>

<body>
    <div id="root">
        姓：<input type="text" name="" v-model="firstName" id=""><br><br>
        名：<input type="text" name="" v-model="lastName" id=""><br><br>
        姓名:{{fullName}}
        <input type="text" v-model="fullName">
    </div>
</body>

<script>
    Vue.config.productionTip = false
    let vm = new Vue({
        el: "#root",
        data: {
            firstName: "",
            lastName: "",
        },
        computed: {
            fullName: {
                get() {
                    return this.firstName + "-" + this.lastName
                },
                set() {
                    let arr = val.split("-")
                    this.firstName = arr[0]
                    this.lastName = arr[1]
                }
            }

        },
    })
</script>

</html>